Preparation of spray dried soap particles having only slight dustforming tendencies



Patented July 8, 1947 PREPARATION OF SPRAY DRIED SOAP PAR- TICLES HAVING ONLY SLIGHT DUST- FORMING TENDENCIES Robert Franklin Heald, Nutley,

J., assignors Givan, Orange, N.

Palmolive-Feet Company, corporation of Delaware and Minor Leslie to .Colgate- Jersey City, N. 3., a

No Drawing. Application April 17, 1941, Serial N0. 388,989

6 Claims. (01. 252-126) The present invention relates to a process treating detergents to reduce dust and lumping tendencies therein, and, more particularly, of incorporating petroleum oil fractions in sprayed, granulated and chip soaps, and to the product of such process.

Spray dried soaps have been employed for both industrial and domestic uses for many years, because of their relative ease of solution, due to the large surface area exposed in this form of soap. Chip soaps and granulated soaps have similarly been used for the same reason. Up to the advent of the present invention. there were attendant disadvantages in the use of these materials which considerably limited their employment. Because of their reduced size, there is always a certain amount of fines, which causes a dust nuisance. This dust is objectionable both from the standpoint of cleanliness and because it acts as an irritant upon the mucous membrane of the user.

The spray dried soaps have the further disadvantage of showing considerable lumping tendencies, that is. the tendency of the soap to lump or agglomerate in" water. This tendency is evident in fatty acid soaps and is of particularly objectionable magnitude in the presence of sol uble salts of the phosphoric acids, such as are frequently employed as soap builders and water softeners. With the fine particles which occur in normal production, a small amount of water causes a heavy gel to form between said particles,- so that they are not so free to dissolve as in their original form. These lumps are difficult to disperse. even upon vigorous agitation. ;The lumps are undesirable, because they have a tendency to stick to articles put into the water and because, being undissolved and therefore unavailable, they considerably reduce the eficiency of the soap. This is particularly true in domestic use, where no real attempt is made to put these lumps into solution.

' the use of fatty acid soaps. This wasdue to the fact that the most troublesome or irritating dust is produced by the breaking down'of the coarser particles during normal handling, resulting in a paticularly fine powder, very small in percentage but very objectionable because of fineness and number ,of particles. Although this problem is an old one in the industry and although many suggestions and proposals have been made for solving it, none, so far as we are aware, has given a satisfactory solution upon a practical and industrial scale.

We have discovered a novel and fully satisfactory method It is an object of our invention to provide an improved process for treating soaps in the manufacture of sprayed, granulated and chip soaps to reduce dust therein while retaining or even increasing the proportion of fines, whereby soap grains and chips having greatly reduced irritant effect in use are produced.

It is also an object of a process for preparing sprayed soap, granulated soap and the like having reduced lumping tendencies therein.

vAnother object of this invention is to providev a comminuted soap product having reduced lumping characteristics.

We also intend to provide chip soap and granulated soap of high washing efficiency having at most only slight tendency to raise dust in use.

Our invention further provides soap grains and beads of high washing efiiciency having at I most only slight dust and lumping tendencies.

Other objects and advantages of the present invention will be apparent to those skilled in the art from the following description,

Broadly stated, according to the present invention, we have found that the addition of a relatively small proportion of a petroleum oil fraction to soap material results in a composition having considerably less tendency to form dust or to lump. A remarkable feature of our operation and was far from being a completely satisfactory solution to the problem. Thus, while the lumping was considerably reduced, the removal of. fines in any practical degree had little effect upon the amount of dust raised in invention is that the addition of the oil has little or no apparent effect upon the washing efiiciency. Furthermore, although the presence of the oil would normally be expected to prevent wetting of the soap particles, another surprising feature of the invention is that the oil actually appears to increase the speed of wetting, with consequent decrease in lump formation.

for solving this prior art problem.

this invention to provide We have also discovered that the amount of dust present in comminuted soaps cannot be directly correlated to the proportion of fines. is not the screenabl fines nor the percentage of fines which determines the tendency to dust, but rather the fineness of the particles and their numerosity in a given quantity of soap.

Arbitrary tests for comparing the tendency of various materials to form dust or to lump have been set up, and it is believed that these tests provide good indices of these characteristics in the materials tested. In the lumping test, 15 gms. of the material to be tested are poured upon the surface of a liter of water at 50 C. The material is allowed to stand one minute and is then vigorously stirred for ten seconds. The resulting mixture is poured through ax10 screen, the foam is blown away, and the material retained upon the screen .is weighed in its wet form. The weight is taken as a measure of the lumping tendency of th particular material.

The dust forming test is a visual test. The material to be tested is poured into a large funnel, the tip of the stem of which is 12 inches above the bottom of a receiving vessel. The soap is suddenly dropp d through the funnel into this vessel, and the extent of the cloud of dust which arises is observed.

It is believed that the presenc of mineral oil upon the surface of the soap particles prevents them from forming a heavy gel between adjacent particles. Du to the oil, the particles are not linked together, and the soap can spread out over the water and be wetted. While the efiect of the oil appears to be primarily a surface phenomenon, we have made the surprising discovery that the oil fraction employed can be incorporated in the'soapv before it reaches its final form, rather than applied to its surface, and that the same proportion of mineral oil gives practically the same result in both instances.

The incorporation of mineral oil is particularly advantageous in the manufacture of chip, granulated and spray soaps. One method of adding the oil in making our improved spray soap comprises spraying the soap into an air stream in a tower and passing the resulting soap grains to a cooling chamber in the usual manner, and then spraying oil upon th soap during the cooling operation. This method of incorporatin v the mineral oil by spraying is also employed by us in reducing the dust otherwise occurring in a soap product resulting from the granulation of a mechanical mixture of soap chips and dry builders, such as orthosilicate, soda ash and other fillers. In general, in the manufacture of soap products other than mechanical mixes, we have found it preferable to add the mineral oil in bulk to the soap material before it is dried, as this method is cheaper and more convenient. Thus, the addition of the mineral oil to the crutcher mix has required no greater proportion of oil and has, in practice, yielded equally satisfactory results. Similarly, the mineral oil can be mixed with the tallow and passed into the kettle before the saponification step in the soap manufacture.

In selecting a petroleum fraction for use in our novel process, we have found the kerosene (astral 011), white mineral oil, and heavy mineral oils of various viscosities are especially suitable for reducing dust and lumping tendencies when incorporated in soap. Of these, the higher fractions have proved somewhat more desirable in that smaller proportions of the oil can be used and that there is less odor. Specifications for suitable oils successfully employed by us are as follows:

KEROSENE' A. P. I. gravity 46.0 Flash point 127 Initial boiling point -..F 350 Final drop ..F 536 WHITE MINERAL On.

Specific gravity, 15.6 0.845 to 0.855 Viscosity Saybolt, 100 F sec to Initial boiling point F 5'72 90% distilled at F 748 Residue per cent-.. 10

HEAVY MINERAL OILs No. l N o. 2 No. 3

A. P. I. gravity 28.5 21. 0 26.0 Flash point, F 300 365 385 Viscosity Saybolt, 100 F., s 75-80 205 3003l5 Initial boiling point, F. 568 600 597 Final distillation point, F 754 737 711 Distilled, per cent 80 40 Residue, per cent 5 20 60 Still higher boiling fractions, having Saybolt viscosities of more than 600 seconds, give very satisfactory results.

It is advantageous to employ oils with flash points high enough to avoid fire hazards, especially where the oil is incorporated in the soap before spraying, as the high temperature of the spraying tower must be taken into consideration.

Using such oils as hereinbefore described, proportions of the mineral oil on the basis of the finished soap productrange from about 0.5 to about 8.0%. Proportions within these limits have been found to reduce the dust and lumping tendencies in the soap. When using oils of relatively high boiling fractions, we have found about 0.5 to about 3.0% to be suitable, and we prefer to use about 0.5 to about 1.5% of mineral oils of this type; this proportion has been found to decrease dust and lumping to a minimum, without affectin the detergent properties and handleability of the soap material. It will be understood that larger proportions of mineral oil must be employed where lighter fractions are incorporated in soap, and, in some cases, even several per cent, say, as much as about 2.5 to about 8%, have been found necessary to reduce dust and lumping to the considerable degree desired. Below the optimum proportion of mineral oil, of the preferred type, the best results are not obtained; above this proportion, the treated soap exhibits a certain stickiness, which is undesirablefrom the standpoints of both the consumer and the packager, and the detergency value of the soap is deleteriously affected.

A sample of untreated sprayed soap grains produced in a tower was found to give a sieve analysis as follows:

TABLE 1 Sieve Per cent On 12 mesh On 20 mesh On 40 mesh. On 60 mesh On 80 mesh-.- On mesh... Through 100 mesh.

'gms. The

This material, despite the relatively low per centage of fines, gave a considerable dust cloud when dropped through the 12-inch distance, described in connection with the dust test supra. The material also showed lumping or about 10.0 foregoing is a typical example of the material produced in a spray tower. There is, however, considerable variation in sieve analyses among materials of this type, the proportion on. the o-mesh sieve usually being of the order of about 45 to about 60% of the material and the proportion on .the 60-mesh sieve running about 25 to about 35%. The fines, that is, material on 100-mesh and material through 100-mesh, each usually run about 1 to about 3%, thus varying in total from about 2 to about 6%. Lumping is of the order of about 8.0 to about 12.5 guns. in this material, as measured by the lumping test described supra.

Another sample of spray dried soap grains produced without oil treatment was tested and found to show lumping of 12.0 gms. Portions of this sample were sprayed, respectively, with 0.4, 0.8 and 1.2% of white mineral oil. The lumping dropped continuously under this treatment, giving the following results:

TABLE 2 Lumping test Lum in Per cent white mineral oil l Another sample of spray dried soap grains, commercially produced, was found to have 12.5

gms. of lumping when untreated. After spraying with 0.6% of white mineral oil at the cooler, the

Taupe 3 Sieve Per cent On 12 mesh On 20 mesh sh Through 100 mesh The addition of mineral oil to the soap material before spraying seems to produce no appreciable efiect in the sieve analysis. Thus, when about 1.5% of heavy mineral oil is added to the mixture in the crutcher and the soap is passed 1 to the tower thereafter and sprayed in the usual manner, the sieve analysis is about as follows, when employing the modified method referred to in the preceding paragraph:

2,4aa44o TABLE 4 Although, as seen from this sieve analysis, the addition of mineral oil does not appreciably affect the amount of fines in the soap, the dust which arises u'pon dropping this oil-treated material through the 12-inch distance is almost negligible, and the lumping is also appreciably reduced. Whereas the untreated material showed lumping of about 8.0 to about 12.5 gms., the addition of 1.5% of our preferred heavy mineral oil to the soap reduces the lumping to about 2.0 to about 5.0 arms; a typical soap produced about 3.5 gms. of lumping. Under controlled conditions, where the untreated material is carefully produced, the lumping can be brought down to about 5.5 to about 7.5 gms., an average of 6.5 gms. of lumping. Under similar conditions, the addition of 1.5% of the preferred mineral oil reduces the lumping to between about 0.5 and about 1.0 gm.

A more detailed understanding of our'invem tion by those skilled in the art may be had from-' the following illustrative examples:

Example I The following ingredients are put into the crutcher and mixed together:

Per cent Kettle soap About 70. 00

Water About 20.6% Anhydrous soa About 47. 8% Unsaponifiables About 1.0% Salt, glycerme, et About 0. 6% 38% sodium silicate solution. About 12.43 Soda ash About 5. 89 Water About 11.68

This mixture is then passed to a spray tower, sprayed into a stream of air therein and passed to a cooler, all in the usual manner. About 32.54% moisture is lost in the tower, producing soap beads having about 10.8% moisture. In the cooler about 2.0% of white mineral oil having a specific gravity of about 0.85 is' sprayed upon the soap heads. Perfume can be added to the crutcher mix or sprayed upon the beads, either separately or in admixture with the mineral oil. The cooling and other operations connected with the product are conducted in a manner well known to those skilled in this art. The resulting product has high washing efiiciency, very little lumping tendency, and only slight tendency to raise dust in use. The soap beads or grains produced are devoid of stickiness and can be easily packaged and conveniently handled. An analysis of 7 this product is as follows: A

100.0 Example II In a, further modification of our invention, the

following components are mixed in thecrutcher:

Per cent About 65. 39 About 19. 2% About 44. 6% About 1.07%" Salt, glycerlne, etc About 0.52% 38% sodium silicate solution About 11.5 Soda as About 5.6 ater AAtbouit Tetrasodium pyrophosphate ou Mineral oil (No. 3) About 0. 71

Per cent Moisture About 12.0 Anhydrous soap About 62. 8 Unsaponifiables (from kettle soap About 1. Unsaponifiables (as mineral 011) About l .0 Tetrasodiuru pyrophosphate..- About 1. 9 Sodium carbonate About 7.9 Sodium silicate About 6.3 Salt, glycerine, etc About 0.0

Example III A like product can be obtained when the mineral oil is added to the partly finished soap in the kettle. Thus, about 1.32 parts of mineral oil, such as the No. 1 mineral oil described, are added to 98.68 parts of unfinished kettle soap having the following constituents on the finished kettle soap basis:

- Per cent Water About 29.01 Anhydrous soap About 67. 36 Unsaponifiables (from fat stocks)... About 1.50 Salt, glycerine, etc About 0.81

The soap is then finished in the kettle in the customary manner and used in a crutcher mix having the following proportions:

' Per cent Kettle soap, as above About 80.00 38% sodium silicate solution. About 8.28 Soda ash r e About 3. 93 Water About 7. 79

The crutcher mix is crutched as usual and is then sent to the tower for spraying and subsequent treatment, as is well known to those skilled in the art, losing about 29.04% moisture. The analysis of the spray dried material follows:

Per cento Moisture About 10. 9 Anhydrous soap About 75. Unsapouifiables (from fat stoc About 1. 7

Unsaponifiables (as mineral oil) Sodium carbonate Sodium silicate About 414. Salt, glycerine, etc About 1.0

Example IV 8 ing the following ingredients in the crutcher, perfume being added as desired:

Per cent Kettle soap About 96. 12

Water About 32.8% Anhydrous soap About 61. 97 Unsaponifiables About 0.7% Salt, glycerine, etc About 0.7%

38% sodium silicate solution About 3. 15

Mineral oil About 0.73

Upon being dried, there is a moisture loss of about 29.1%. The dried chips have the following analysis:

Per cent Moisture About 8.0 Anhydrous soap About 87. 3 Unsaponifiablcs (from kettle s p) About 1 0 Unsaponifiables (as mineral oil) About 1,0 Sodium silicate About 1.7 Salt, glycerine, ctc About 1.0

This product has very little tendency to dust, giving only a negligible amount of dust when submitted to the dust test described, and it shows high washing efiiciency.

In selecting a. mineral oil for us in our novel soap composition, we have found that the viscosity of the oil is not of great effect, although slightly better results have been obtained with oils of higher viscosity. This may be due, in part, to the fact that these oils in general represent higher fractions. It has been observed in this connection that, if the oil is too viscous, it is difficult to handle and can therefore b inconvenient.

It will be observed that the results which we have obtained with our novel soap composition and with our new soap products are superior to those obtained by the prior art. Even where the fines and dust in powdered soap or soap grains have been eliminated by sizing and processing to a point where only about 1.2% passes through the -mesh screen, we have found by our standard test, described supra, that the dust raised with this material is much greater than with the oiltreated material of the present invention. Moreover, the tendency of our soap composition and spray dried soap to lump in water is far below such tendency in untreated soaps having an equivalent amount of fines. Indeed, by incorporating mineral oil in our soap composition, we have found it practical and feasible to permit the presence of more fines in the spray material. as the dust is too slight to be objectionable. These fines actually provide a superior soap product, as the speed of solution of the material is increased.

We have found that a portion of the mineral oil in our novel product can be replaced by materials, such as sodium chloride, which have a salting out effect. Thus, in general, the addition of about 2.0% of salt permits a reduction in mineral oil to about 0.5%, based upon the weight of the final product. While the introduction of salt into a soap composition has been observed to have little effect upon the dust tendency of products made therefrom, it is believed that the salt acts as an aid in preventing lumping.

The present invention has been described with reference to illustrative examples and proportions, but it will be appreciated by those skilled in the art that other variations and modifications of our invention can be employed, without departing from the principles thereof. Thus, it will be understood that our invention is not limited to the particular types of soap set forth produced.

in our illustrative examples nor to the particular ingredi nts therein recited. Our improved process is as fully applicable to the manufacture of all kinds of soaps and soap compositions, whether produced by saponification of fats, fatty oils and waxes, such as tallow, coconut oil, olive oil, palm oil, castor oil, garbage grease, wool fat, cottonseed oil or foots, whale oil, fish oils, spermaceti, etc.,

or by neutralization of the various fatty and resin acids in these and other materials. Similarly, our novel soaps and soap compositions may contain any of the soap builders and fillers usually employed by the art. I

By the term particle used in the appended claims, we intend to include sizes and shapes of material having at least one dimension of relatively low order, such as grains, beads, chips, flakes and other forms having proportionately large surface area. Similarly, the term comminuted as applied to soaps and other detergents is intended by us to include those forms having at least one small dimension. Particles having solid centres are usually referred to as grains, while hollow particles are generally known as beads. Grains and beads frequently occur together and are distinguishable from chips and flakes in that all of their dimensions are of relatively low order.

We claim:

1. A process of treating soap in the form of spray dried particles to reduce the dust-forming and lumping tendencies thereof which comprises spraying said spray dried particles after formation with about 0.5% to 3% of a heavy mineral oil fraction, said percentage being based upon the amount of mineral oil in the final product, whereby improved particles having only slight dust-forming and lumping tendencies are produced.

2. A process of treating soap in the form of spray dried particles to reduce the dust-forming and lumping tendencies thereof which comprises spraying about 0.5% to 8% of a mineral oil fraction having an initial boiling point of at least about 350 F. upon spray dried soap particles wherebyspray dried soap particles having reduced' dust-forming and lumping tendencies ar 3. A process of preparing soap in spray dried particles which comprises preparing soap for spray drying, mixing with said soap about 0.5% to 3% of a heavy mineral oil fraction, said percentage being based upon the amount of mineral oil in the final product, and then spray drying said mixture, whereby spray dried soap particles having only slight dust-forming and lumping tendencies are produced.

4. The process of preparing spray-dried soap the form of particles having only slight dust-forming and lumping tendencies which comprises mixing about 0.5% to 8% of a mineral oil fraction having an initial boiling point of at least about 350 F.

with soap of spray drying composition, said percentage being based upon the amount of mineral oil in the final product, and then spray drying said mixture.

5. A process of preparing spray dried soap particles in the form of beads having only slight dust-forming and lumping tendencies which comprises mixing about 0.5% to 8% of a mineral oil fraction having an initial boiling point of at least about 350 F. with'a soap of spray drying composition, said percentage being based upon the amount of mineral oil in the final product, and then spray drying said mixture under conditions that produce particles in the form of beads.

6. A process of preparing spray dried soap particles in the form of grains having only slight dust-forming and lumping tendencies which comprises incorporating about 0.5% to 8% of .a mineral oil fraction having an initial boiling point of at least about 350 F. in a soap of spray drying composition, said percentage being based upon the amount of mineral oil in the final product, and then spray drying said composition under conditions that produce particles in the form of grains.

ROBERT FRANKLIN HEAID. MINOR LESLIE GIVAN.

REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Date Number Name 1,719,251 Weber July 2, 1929 1,715,999 Flammer et al. June 4, 1929 2,058,781 Ellis Oct. 27, 1936 2,130,362 Muncie Sept. 20, 1938 1,946,863 Koenders Feb. 13, 1934 1,886,632 Broeman Nov. 8, 1932 1,479,757 Trent Jan. 1, 1924 2,016,289 McGill Oct. 8, 1935 2,296,121 Smith Sept. 15, 1942 2,206,289 McDaniel July 2, 1940 FOREIGN PATENTS Number Country Date 23,054 Great Britain 1894 OTHER REFERENCES Washing, Cleaning and Polishing Materialscircular 0424, U. S. Bureau of Standards (1939), Page 19. 

